A study of the practice of systems engineering across commercial and public interest domains shows that the basic principles of systems engineering are present in all domains, but that each domain brings with it unique aspects. Domains studied include commercial aircraft, facilities, telecommunications, highway transportation, resource management, plutonium disposal, facilities, hightechnology transit buses, motor vehicles, design for environment, and the legal system. Aspects examined are the system life cycle, the system functions, the system architecture, and the requirements drivers. This analysis finds that commercial and public interest domains are dominated by one or more of the following considerations: competitive market price pressures, diverse governmental and public input, existing and developing certification and regulatory standards, the introduction of new technology, and the requirement to serve multiple users.